using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SharpChat {
    public class ChatChannel : IPacketTarget {
        public string Name { get; set; }
        public string Password { get; set; } = string.Empty;
        public bool IsTemporary { get; set; } = false;
        public int Rank { get; set; } = 0;
        public ChatUser Owner { get; set; } = null;

        private List<ChatUser> Users { get; } = new();

        public bool HasPassword
            => !string.IsNullOrWhiteSpace(Password);

        public string TargetName => Name;

        public ChatChannel() { }

        public ChatChannel(string name) {
            Name = name;
        }

        public bool HasUser(ChatUser user) {
            return Users.Contains(user);
        }

        public void UserJoin(ChatUser user) {
            if(!user.InChannel(this)) {
                // Remove this, a different means for this should be established for V1 compat.
                user.Channel?.UserLeave(user);
                user.JoinChannel(this);
            }

            if(!HasUser(user))
                Users.Add(user);
        }

        public void UserLeave(ChatUser user) {
            Users.Remove(user);

            if(user.InChannel(this))
                user.LeaveChannel(this);
        }

        public void Send(IServerPacket packet) {
            foreach(ChatUser user in Users)
                user.Send(packet);
        }

        public IEnumerable<ChatUser> GetUsers(IEnumerable<ChatUser> exclude = null) {
            IEnumerable<ChatUser> users = Users.OrderByDescending(x => x.Rank);

            if(exclude != null)
                users = users.Except(exclude);

            return users.ToList();
        }

        public string Pack() {
            StringBuilder sb = new();

            sb.Append(Name);
            sb.Append('\t');
            sb.Append(string.IsNullOrEmpty(Password) ? '0' : '1');
            sb.Append('\t');
            sb.Append(IsTemporary ? '1' : '0');

            return sb.ToString();
        }

        public bool NameEquals(string name) {
            return string.Equals(name, Name, StringComparison.InvariantCultureIgnoreCase);
        }

        public override int GetHashCode() {
            return Name.GetHashCode();
        }

        public static bool CheckName(string name) {
            return !string.IsNullOrWhiteSpace(name) && name.All(CheckNameChar);
        }

        public static bool CheckNameChar(char c) {
            return char.IsLetter(c) || char.IsNumber(c) || c == '-' || c == '_';
        }
    }
}